This disclosure relates generally to a computing system, and more particularly to a mobile computing system integrating dissimilar systems within a system. In general, mobile computing systems provide either specialized functionality and relatively long interval between battery charges, or the mobile computing systems provide full range functionality with relatively short battery charge lifetime. In addition, the mobile computing system with specialized functionality is available for user interaction immediately upon activation of the system.
There are currently two popular types of mobile computing systems. The mobile Personal Computer (PC) system is a fully functional data processing system, typically having the same functionality as a desktop PC or a workstation PC. The mobile PC system is typically referred to as a notebook or laptop computer. The mobile PC system type runs under any number of standard operating systems, such as one of the releases of Windows(copyright) by the Microsoft Corporation. In implementing the mobile PC in a mobile computing system, several relatively undesirable features are apparent. First, the batteries of the portable mobile PC device must be recharged after a relatively short time, typically, in the order of a few hours. Despite improvements in battery technology, the quest for lighter and more compact portable units have tended to reduce the space allocated to the batteries so that time between charging of the batteries has not been significantly improved. The batteries used in the portable mobile PC devices, however, are capable of relatively rapid charging. As with the desktop PC unit and the workstation PC from which they are derived, the operating system needed for the mobile PC system requires a relatively long time from the activation of the power switch to the time when the processing system is available for actual computation. The mobile PC systems, however, have remarkable flexibility and can provide processing capability of extraordinary power.
More recently the personal digital assistant (PDA) system has been developed to take advantage of operating systems (OS) such as Palm(copyright) OS and Windows(copyright) CE. These operating systems, in conjunction with a PDA system, permit a reduced or specialized functionality computing system.
Typically, these PDAs are relatively small and can perform a variety of useful functions such as arrange calendars; schedule appointments; send and receive e-mail; provide presentations; create documents; and provide communications. The PDA operating systems can permit exchange of files between the PDA systems and a mobile PC system with Microsoft Windows(copyright) files. While the reduced functionality can be a disadvantage of the PDA system, this system has several advantages. An advantage is the time between charging of the batteries can be greatly extended, a result of the reduced functionality and the absence of disk storage units. A PDA system has considerable flexibility with respect to expansion. However, as the system is expanded, the power requirements increase, and the battery charging cycle is decreased. The time for charging the batteries, at least on the presently available PDA systems, requires a relatively long period. Another advantage is the PDA system has the memory loaded in the memory circuit, such as a flash memory, as contrasted with a disk drive for the mobile PC devices. Compare this process to the time of activation for a mobile PC. For reasons related to testing, to flexibility and to backward compatibility, a relatively large amount of time elapses between the activation of a mobile PC device and when the device is functional. In contrast, the PDA system is fully functional from the time that it is activated.
A need has been felt for a mobile computing system having the desirable features of both the mobile PC systems and of the PDA systems. In particular, the mobile computing system would have the feature of an expanded time between battery charges. Another feature of the mobile computing system would be the availability for performing user-directed processing functions as soon as the power is applied to the processing unit made available by a PDA system. Another feature of the portable processing unit would be the capability of performing essentially all of the processing functions available to the full-function PC system. Still another feature would be a low-power, reduced functionality mode of operation and an increased power, full functionality mode of operation. Yet another feature of the portable data processing system would be the ability to control mode of operation, i.e., a low power, reduced-functionality mode or a high power, full-function mode of operation.
The aforementioned and other features are accomplished, according to the present disclosure, by providing a mobile computing system that includes a PC system and a PDA system which can share common resources within the mobile computing system and a communication bus.
For applications not requiring the full functionality of the mobile PC system, a user can select the PDA system in conjunction with a common display and shared peripheral devices, providing a reduced power mode operation of the computing system. When expanded functionality is required of the computing system, the mobile PC system is activated or given control. The user has selectable control over whether the PC system or the PDA is activated.
The user has the option of transferring control of the common display and control of the shared peripheral devices. During power-up, the PDA system, common display and shared peripheral devices are automatically activated, thereby providing an instant-on function. The user, however, has the option as to how to configure the data processing system default parameters.
The user enters a command as to which system is to have control over the common resources. The PC system or PDA system processes this command and initiate transfer of the common display and shared peripheral devices to the other system. When the PDA system is given control, the communication bus to the PC system is blocked, allowing the PDA system control over the shared peripherals. The PDA is also given control over the common display device. The PDA system contains individual memory storage, including memory related to start-up instructions.
While the PDA system is in control, the PC system operates in one of several restricted modes. Some of these modes include a power off state where all PC system only devices are powered down, a suspend state where the PC system does not execute and has a limited number of devices in a low power mode, or full power but cripled state where the shared resources and the PDA system are not available to the PC system.
When the PC system is given control, the PDA system becomes a slave resource of the PC system and the PC system is given control over the shared peripheral devices. The PC system is also given control over the common display device. The PC system has individual memory storage which includes start-up instruction code.
Control over which system has control over the shared resources can be done by a shared resource such as an Embedded Controller (EC). The EC acting under direction of either the PC system or the PDA system, directs control of the shared peripheral devices to the correct system.
The EC also controls the routing of the shared communication channel to allow the logical, electrical, and/or functional isolation needed for the correct operations of the mobile computing system.